As used herein, a "semiconductor device" is a silicon chip (die) containing circuit elements. A "semiconductor device assembly" is a silicon chip contained within a package and connected (wired or bonded) to conductive leads which exit the package.
Heat is inevitably generated during operation of a semiconductor device, and may become destructive of the device if left unabated. Therefore, it is generally well known to provide some sort of heat sink for semiconductor devices. Generally, heat sinks take one of two forms. They may be integral with the device package (assembly) or they may be external to the device package. The present invention is related to integral heatsinks that form part of the semiconductor device assembly. In either case, heat sinks generally include at least a heat-dissipating plate in intimate heat conductive relationship to the semiconductor device.
The problem of heat dissipation is especially relevant in semiconductor devices that have a high lead count or which operate at high speeds, both of which factors contribute significantly to the generation of heat by the device.
U.S. Pat. No. 4,803,546 discloses a heatsink package for flip-chip integrated circuits (ICs). A semiconductor element (die) 11 is mounted face (circuit side) downward on a substrate 12. The circuit elements on the die face the substrate, which has interconnects formed on its die-facing surface. A generally flat heatsink member 14 is soldered onto the back (circuitless) side of the die.
U.S. Pat. No. 4,340,902 discloses a chip 102 mounted on a plate 110. The plate 110 is mounted to another plate 100 which is mounted with resin or solder 114 to cooling means 107,108.
Japanese Patent Publication No. 59-117244 discloses a pellet (die) 30 bonded to the exposed surface of a heat sink 27.
While the references cited above show various techniques of mounting semiconductor dies, there is a need for a technique of providing an efficient heat sink structure in conjunction with board-mounted devices.